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871.
The hyperbranched polymers can be made by self-condensing vinyl polymerization without gelation transition. The average molecular weights, as well as the average sizes, can reach infinite values as the reaction is quantitatively completed, and the scaling forms of the molecular parameters should exist. In the paper, based on a recursion formula, the scaling form of the number fraction distribution and the number of the n-mers are given analytically as the conversion of double bonds is near 1. The mean square radius of gyration for very large hyperbranched polymers is calculated explicitly to give a scaling exponent. Finally, a scaling relation associated with the fractal dimension and the polydispersity exponent is given clearly.  相似文献   
872.
Multibody systems including impacts with friction possess a rich dynamical structure, mainly due to their non-smooth and therefore highly nonlinear characteristics together with the variety of multiple contact possibilities. Existing theories describe such situations efficiently and correctly as has been proven by many practical applications. It can be shown, that even in large multibody systems with many possible impacts very seldom two or more impacts occur at exactly the same time, usually impacts are separated from each other. From this it makes sense to consider in more detail the structure of one impact alone and to investigate the functional dependencies with respect to the initial magnitudes, namely normal and tangential relative velocities and normal and tangential impulses before an impact. This paper describes the theory and gives examples.  相似文献   
873.
The aim of the paper is to explain new concepts of solutions for n-persons fuzzy games. Precisely, it contains new definitions for ‘core’ and ‘Shapley value’ in the case of the n-persons fuzzy games. The basic mathematical results contained in the paper are these which assert the consistency of the ‘core’ and of the ‘Shapley value’. It is proved that the core (defined in the paper) is consistent for any n-persons fuzzy game and that the Shapley values exists and it is unique for any fuzzy game with proportional values.  相似文献   
874.
875.
Divergence of a Random Walk Through Deterministic and Random Subsequences   总被引:1,自引:0,他引:1  
Let {S n} n0 be a random walk on the line. We give criteria for the existence of a nonrandom sequence n i for which respectively We thereby obtain conditions for to be a strong limit point of {S n} or {S n /n}. The first of these properties is shown to be equivalent to for some sequence a i , where T(a) is the exit time from the interval [–a,a]. We also obtain a general equivalence between and for an increasing function fand suitable sequences n i and a i. These sorts of properties are of interest in sequential analysis. Known conditions for and (divergence through the whole sequence n) are also simplified.  相似文献   
876.
We obtain outer rates of clustering in the functional laws of the iterated logarithm of Deheuvels and Mason(11) and Deheuvels,(7) which describe local oscillations of empirical processes. Considering increment sizes a n 0 such that na n and na n(log n)–7/3 we show that the sets of properly rescaled increment functions cluster with probability one to the n-enlarged Strassen ball in B(0, 1) endowed with the uniform topology, where n 0 may be chosen so small as (log (1/a n) + log log n)–2/3 for any sufficiently large . This speed of coverage is reduced for smaller a n.  相似文献   
877.
I consider the problem of computing the space of conservation laws for a second-order parabolic partial differential equation for one function of three independent variables. The PDE is formulated as an exterior differential system on a 12-manifold M, and its conservation laws are identified with the vector space of closed 3-forms in the infinite prolongation of modulo the so-called "trivial" conservation laws. I use the tools of exterior differential systems and Cartan's method of equivalence to study the structure of the space of conservation laws. My main result is: Theorem. Any conservation law for a second-order parabolic PDE for one function of three independent variables can be represented by a closed 3-form in the differential ideal ${\cal I}$ on the original 12-manifold M. I show that if a nontrivial conservation law exists, then has a deprolongation to an equivalent system on a 7-manifold N, and any conservation law for can be expressed as a closed 3-form on N that lies in . Furthermore, any such system in the real analytic category is locally equivalent to a system generated by a (parabolic) equation of the formA (u xx u yy -u 2 xy )+Bu xx +2Cu xy +Du yy +E = 0 where A, B, C, D, E are functions of x, y, t, u, u x , u y , u t . I compute the space of conservation laws for several examples, and I begin the process of analyzing the general case using Cartan's method of equivalence. I show that the non-linearizable equation has an infinite-dimensional space of conservation laws. This stands in contrast to the two-variable case, for which Bryant and Griffiths showed that any equation whose space of conservation laws has dimension 4 or more is locally equivalent to a linear equation, i.e., is linearizable.  相似文献   
878.
In this paper we are concerned with the problem of solving numerically isospectral flows. These flows are characterized by the differential equation

where is a symmetric matrix, is a skew-symmetric matrix function of and is the Lie bracket operator. We show that standard Runge-Kutta schemes fail in recovering the main qualitative feature of these flows, that is isospectrality, since they cannot recover arbitrary cubic conservation laws. This failure motivates us to introduce an alternative approach and establish a framework for generation of isospectral methods of arbitrarily high order.

  相似文献   

879.
Let K be a function field and C a non-isotrivial curve of genus g2 overK. In this paper, we will show that if C has a global stable modelwith only geometrically irreducible fibers, then Bogomolov conjecture over function fields holds.  相似文献   
880.
Characterizations of quantum bordisms and integral bordisms in PDEs by means of subgroups of usual bordism groups are given. More precisely, it is proved that integral bordism groups can be expressed as extensions of quantum bordism groups and these last are extensions of subgroups of usual bordism groups. Furthermore, a complete cohomological characterization of integral bordism and quantum bordism is given. Applications to particular important classes of PDEs are considered. Finally, we give a complete characterization of integral and quantum singular bordisms by means of some suitable characteristic numbers. Some examples of interesting PDEs which arise in physics are also considered where existence of solutions with change of sectional topology (tunnel effect) is proved. As an application, we relate integral bordism to the spectral term that represents the space of conservation laws for PDEs. This also gives a general method to associate in a natural way a Hopf algebra to any PDE.  相似文献   
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